Normal growth, as well as tissue repair and remodeling, require specific and delicate control of activating growth factors and their receptors. Fibroblast Growth Factors (FGFs) constitute a family of over twenty structurally related polypeptides that are developmentally regulated and expressed in a wide variety of tissues. FGFs stimulate proliferation, cell migration and differentiation and play a major role in skeletal and limb development, wound healing, tissue repair, hematopoiesis, angiogenesis, and tumorigenesis (reviewed in Ornitz, Novartis Found Symp 232: 63-76; discussion 76-80, 272-82 (2001)).
The biological action of FGFs is mediated by specific cell surface receptors belonging to the Receptor Protein Tyrosine Kinase (RPTK) family of protein kinases. These proteins consist of an extracellular ligand binding domain, a single transmembrane domain and an intracellular tyrosine kinase domain which undergoes phosphorylation upon binding of FGF. Four FGFRs have been identified to date: FGFR1 (also called Flg, fms-like gene, flt-2, bFGFR, N-bFGFR or Cek1), FGFR2 (also called Bek-Bacterial Expressed Kinase-, KGFR, Ksam, Ksaml and Cek3), FGFR3 (also called Cek2) and FGFR4. All mature FGFRs share a common structure consisting of an amino terminal signal peptide, three extracellular immunoglobulin-like domains (Ig domain I, Ig domain II, Ig domain III), with an acidic region between Ig domains (the “acidic box” domain), a transmembrane domain, and intracellular kinase domains (Ullrich and Schlessinger, Cell 61: 203, 1990; Johnson and Williams (1992) Adv. Cancer Res. 60: 1-41). The distinct FGFR isoforms have different binding affinities for the different FGF ligands.
Alterations in FGFRs have been associated with a number of human cancers including myeloma, breast, stomach, colon, bladder, pancreatic and hepatocellular carcinomas. Recently, it was reported that FGFR4 may play an important role in liver cancer in particular (PLoS One, 2012, volume 7, 36713). Other studies have also implicated FGFR4 or its ligand FGF19 in other cancer types including breast, glioblastoma, prostate, rhabdomyosarcoma, gastric, ovarian, lung, colon (Int. J. Cancer 1993; 54:378-382; Oncogene 2010; 29:1543-1552; Cancer Res 2010; 70:802-812; Cancer Res 2011; 71:4550-4561; Clin Cancer Res 2004; 10:6169-6178; Cancer Res 2013; 73:2551-2562; Clin Cancer Res 2012; 18:3780-3790; J. Clin. Invest. 2009; 119:3395-3407; Ann Surg Oncol 2010; 17:3354-61; Cancer 2011; 117:5304-13; Clin Cancer Res 2013; 19:809-820; PNAS 2013; 110:12426-12431; Oncogene 2008; 27:85-97).
Therapies involving FGFR4 blocking antibodies have been described for instance in WO2009/009173, WO2007/136893, WO2012/138975, WO2010/026291, WO2008/052798 and WO2010/004204. WO2014/144737 and WO2014/011900 also describe low molecular weight FGFR4 inhibitors.